Apparatus for cleaning out obstructions from conduits



March 10, 1953 1 v, OBR|EN 2,630,590

APPARATUS FOR CLEANING OUT OBSTRUCTIONS FROM CONDUITS Filed Jan. 15, 1948 Patented Mar. 10, 1953 APPARATUS FOR CLEANING OUT OBSTRUC- TIONS FROM CONDUITS John V. OBrien, Park Ridge, Ill.

Application January 13, 1948, Serial No. 2,037

This invention relates to improvements in appara-tus for cleaning out obstructions from conduits, of which sewers, drains, pipes and the like are examples, and it consists of the matters hereinafter described and more particularly pointed out in the appended claims. i Reference is hereby made to my co-pending application Serial No. 2,038, led on even date herewith, for a method and apparatus of a somewhat similar character. Reference is also madeto my co-pending applicati-on Ser. No. 314,716 led October 14, 1952, which is a division of the present application and relates more particularly to the method for cleaning out obstructions from con-duits.

Heretofore, certain apparatus for this purpose comprised simply a closely wound helical coil having a working or tool carrying end for engagement with the obstruction in the conduit to be cleaned. It has been customary to associate therewith some means for turning the coil vaxially as it is fed through the conduit in the use of the apparatus. In such use, when the work end of the coil engages the obstruction and is hel-d against rotation thereby, continued turning of the remainder of the coil buil-ds up torque, the magnitude of which is dependent upon the power employed to tu-rn the coil and the resistance to turning which the obstruction supplies. When the torque developed is excessive with respect to the particular coil, the elastic limit of the wire in the coils is exceeded and results either in kinking, breakin-g, or otherwise damaging the coil.

When torque is applied to th-e coil in a con-duit and it is torsioned because of the engagement of the working end with the obstruction, it is the practice momentarily to retract the coil to 'loosen the tool or work end in or free it from the obstruction so that the torque causes the working end to rotate rapidly with great force against the obstruction. The tool then cuts through the obstruction or hook-s onto the obstruction so that the material causing the obstruction may be withdrawn with the withdnawalof the coil from the conduit, if its character so permits.

To obtain adequate stiffness in such coils the prior .practice has been to close-wind the coil under tension to such small diameter as to leave a passageway therethrough no larger than the diameter of the wire of which the coil is composed.

9 Claims. (Cl. 15--104.3)

In another prior art constructi-on the coil is wound to a larger diameter and provided with a core upon which the convolutions of the coil are impacted, toafford a `firm and permanent grip thereon.

Neither of these practices is entirely satisfactory for reasons which will be stated later.

Coils for cleaning purposes of this kind are preferably made of a relatively hard steel wire, termed music wire, having an .85 to .95 degree carbon cont-ent. They are produced either by winding the wire upon an arbor in a lathe or winding the wire in a ceiling machine in which the wire is fed with a pushing action against a set of coiling .points or dies, to form the wire into a coil which leaves the machine in a direction at substantially a yright angle to the line of the feed of the wire.

The wire mentioned, which .comes in long lengths, is not always uniform in hardness throughout its length, s-o that certain portions thereof may be softer than others. Therefore, different portions of the wire act differently in ooiling operations.

When the coils are formed to small diameter, in order to obtain the desired stiffness therein,y the metal on the inside of the convolutions is crowded and the metal on the outside of the convolutions is stretched Thus the character of the wire after coiling is substantially different from that before coiling. `Such crowding of the metal on the inside of the convolutions produces fissures and cracks in the coil which reduces the capacity of the coil to withstand the torque imposed upon it in use. Therefore, such coils kink or break more easily than would otherwise be the case. Thus, while coils of smaller diameter afford considerable longitudinal stiffness and have lateral ilexibi'lity, they tend to kink and break prematurely in use and therefore are not wholly satista-ctory.

In order to overcome the disadvantages of the smaller diameter coils, attempts have been made to increase the diameter to the extent necessary to avoid such crowding of the metal. However, when increasing the diam-eter of the coil, formed of a given size wire, the capacity of the coil to transmit the torque necessary to do the work required is reduced. Thus, such coils,

when subjected to the torque necessary to remove ce-rbain obstructions, will collapse, particularly in those convolutions in which the softer metal is present, thus rendering the coil usel-ess for fur-ther work.

Attempts have been made to cure or prevent coils of larger diameter from collapsing by employing a central wire or core around whi-ch the wire of the coil is sol tightly wound that relative longitudinal movement cannot occur between the coil and the embraced core. In use, such coils must 4be able readily to follow around elbows and other bends in a conduit and in such manner that no permanent bend or kink will be formed in they coil. However, when a. coil, having a core so fixed therein that relative longitudinal movement cannot take place between the coil and its core, passes around a bend in a conduit the action results in stretching that part of the core which is on the outside of the bend. As this stretched part of the core cannot return to its normal condition, a permanent kink or bow is developed in the coil, which cannot be straightened out or removed from the coil becausey of the inaccessibility of the core. Such a bow increases the resistance of the coil to rotary and longitudinal movement in a conduit and is otherwise objectionable. Also, such kinking of the coil interferes with the winding or wrapping of the coil in a storage drum or onto a storage reel.

I am also aware that it has -been proposed to make coils of this kind with convolutions of a diameter several times the diameter of the wire of which it is composed. Such coils, while quite flexible, have little longitudinal stiffness and do not have adequate resistance to torque laction. Hence, they tend to collapse prematurely under torque action and when withdrawn from a conduit, they open up between -convolutions and cannot be restored to their original condition. To prevent such coils from opening up when withdrawing the same from a conduit, they have in some instances been provided with a central flexible, but inextensible member of small diameter. However, the function thereof is merely to take the pull from the coil when withdrawing the coil from a conduit to prevent opening of the convclutions thereof. However, this member is so small in diameter relative to the diameter of the coil that it does not afford internal support for r the coil.

One of the objects of the present invention is to provide an elongated coil apparatus of this kind, which may be easily worked into a conduit toward an obstruction therein, which will readily pass around the bends, elbows and other fittings in the conduit, and which at the same time will better withstand the torsion developed when turning the coil about its longitudinal axis while one end is in engagement with said obstruction, all without breaking, kinking or taking on a permarient set or bend.

Another object of the present invention is to provide apparatus of this kind which includes a` coil and associated core that are so related in structure and diametric dimensions that the coil functions substantially as a free coil spring shaft without internal support in the initial part of an obstruction removing operation, and functions in the final part of such operation as an internally supported flexible shaft having increased power transmitting characteristics.

A further object of the invention is to provide apparatus of this kind that includes a coil and a flexible core for use in the bore or passageway of the coil and so related in cross sectional dimensions relative to the fbore or passageway or" the coil as to be capable of a limited longitudinal movement in the passageway or bore when the coil is not subjected to torque but which is gripped by the coil when the latter is subjected to torque of certain magnitude so that the core provides an internal support for the coil, thereby preventing collapse and breakage due to torque action.

Also, it is an object of the invention to provide apparatus of the kind above mentioned, wherein the core is confined against displacement from the coil, but is capable of a limited longitudinal slipping action within the coil, when the latter is not subjected to torque and which core is gripped by the coil when it is subected to torque of predetermined magnitude, thereby affording an internal support for the coil.

The above mentioned objects of the invention, together with others, along with the advantages thereof, will more fully appear as the specification proceeds.

In the drawing:

Fig. 1 is a longitudinal sectional view through the work end of apparatus, substantially on a full size scale, except that the space between the core and the coil is somewhat exaggerated, embodying one form and size of the invention and more particularly showing one way in which the core may be operatively attached to one point in the length of the coil.

Fig. 2 is a transverse sectional view on line 2 2 of Fig. l but on an enlarged scale, through a part of the coil and core, back of the work end of the coil and more accurately showing the annular clearance space between the external surface of the core and the internal surface of the coil when the coil is free from torque.

Fig. 3 is ay view in elevation, better showing the preferred form of flexible core employed with the coil of Figs. 1 and 2 and on a scale enlarged over that of Fig. l.

Figs. 4, 5, 6 and '7 are detail longitudinal sectional views through parts of the coil showing various ways in which longitudinal displacement between the work end of the coil and the core is prevented.

Fig. 8 is a longitudinal sectional view through a part of an obstructed drain and shows one way in which the obstruction may be removed therefrom. by means of the coil and core construction before mentioned and which will be more fully described later.

In general, the improved apparatus includes a closely wound helical coil of desired length and a fiexible core for use in the longitudinal bore or passageway of the coil. Coils of this kind are wound either L.H.helix or R.H.helix. In the trade `a coil designated as being wound L.H.helix refers to one which is wound counterclockwise in the manufacture thereof, and conversely a coil designated as being wound R.H.helix refers to one which is wound clockwise in the manufacture thereof. The coil illustrated herein is one that is wound L.H.helix. The diameter of the core, with reference to that of the bore of the coil, is such that when the core is disposed within the bore, a slight clearance is present therebetween. The coil is provided with a Work end, which is the end first entered into and worked along a conduit, until it reaches the obstruction therein. It is desired that the core be carried in the bore of the coil and in a manner preventing endwise movement of the core rearwardly from the work end, though permitting a limited longitudinal slipping of the core relative to the coil, as when the coil follows a tortuous path in use and as the coil is` inserted in the conduit to be cleaned. It, therefore, is preferred that the core be attached at one point in its length to the coil, adjacent the work end of the coil, so that the core will be pulled along with the coil,

After the coil, with the core disposed in its bore, is located in a conduit with its work end engaged with the obstruction therein, the coil is turned axially either by means of a hand tool or a power tool in the proper direction. Assuming the coil to be wound with left hand helix, as indicated in the drawings, the coil will be turned clockwise, as viewed in Fig. 2, and as indicated by the arrow. With the work end en,- gaged with an obstruction, the axial turning of the coil in the directi-on mentioned, builds up torque in the coil, causing a reduction in diameter to the limit afforded by the slight clearance space between the core and bore of the coil. The coil is thus caused to engage the core throughout its length and be internally supported and reinforced thereby against premature opening up, 'breaking or kinking. However, at the time the coil was being inserted into the conduit, it was l not in gripping contact with the core, and hence acted as a relatively free spring readily able to accommodate itself to the tortuous path usually found in conduits from which obstructions are to be removed. While the diameter of the coil is being reduced, its length is also being increased, but the space between the core and coil permits the necessary slippage between coil and core. Hence, neither the coil nor the core is stretched or strained, so that both return to normal condition after removal from the conduit, provided of course the apparatus be used within the limits for which it is designed.

Referring now in detail to that embodiment of the invention illustrated in Figs. l, 2, and 3 of the drawing, the improved apparatus includes an outer member or envelope I0 in the form of a long coil having an internal bore or passage designed to receive a exible core II.

The coil I0 is preferably made of a so-called music steel wire having a carbon content of 0.85 to 0.95. Such Wire is obtainable in the market, is known to the trade as a bright music wire, and well serves the purpose. Preferably the wire has such a cross sectional shape that the sides of adjacent convolutions thereof may roll relatively in the bending of the coil. Preferably, therefore, and as shown, the wire has a circular cross section.

The coil Ill, which is preferably produced by die coiling machines employing adjustable dies or `coiling points which determine the outside diameter of the coil, includes a relatively long body' I2 having a relatively short tool carrying portion I 3 .at one end. The diameter of the body portion I2 of the coil is dependent upon the type of work for which the apparatus is to be used. In coils of different diameters, preferably different diameters of wire are employed. g

Fig. 1 shows one size of coil, which may be 50, '75 or 100 feet or more in length, and which is well adapted for use in the sewer cleaning` art, especially for the smaller size conduits. The outside diameter of the body I2 of the coil is `6 dependent upon the diameter of the Wire to be used therefor, the outside diameter of the core II to be `used therewith, and the amount of clearance between the coil and core. For a core having an outside diameter of .21T/.219 and using a wire of .138" forr the coil, such wire is tension wound to such an outside diameter as to afford an overall clearance of .005/.007 between the core and the body of the coil. Such a coil body will have an outside diameter approximating one-half of an inch. Assuming the core to be centrally disposed within the coil, there would then be an annular space of .M25/.0035 between the outside surface of the core and the inside surface or bore of the coil.

As shown, the portion I3 of the coil has an inside diameter of about 0.60 inch for one--half its length and gradually decreases in diameter for the other half of its length, to meet the associated end of the body I2 of the coil. In said portion I3 of the coil, the convolutions are closely coiled or wound, but preferably are not in tension, being heated to a straw color to accomplish this result. Thus, this portion, which is the leading end of the coil, has more iiexibility for bending laterally of the axis of the coil and is thus 'better adapted for passage through a conduit having short bends, curves, joints, etc.

The free open end of said portion I3, as shown, has therein a plug I4, which serves to support an obstruction removing tool I5 and which, in this instance, includes a pair of curved cutting arms. Other forms of tools and work ends :may be provided, the form illustrated in the drawing being merely one well adapted for the use intended.

The core II is preferably in the form of a flexible member, such as used for the core part in the drives for speedometer and dental engines. A core which has been found satisfactory cornprises a central wire Ilc and a plurality of multiple spring wire strands IIa with the strands in each layer wound in opposite directions. Material of this kind, which is best illustrated in Fig. 3 and known as speedometer core may be obtained in the open market in various diameters and no claim is herein made to such material, per se.

It will be understood, of course, that the number of layers and the numbers of strands in each layer and the sizes of wire will vary for idifferent or specific sizes. However, it is believed that a general description of certain sizes of cores will be helpful. Hence, the wire requirements for three examples or sizes, known as 220 speedometer core, 187 speedometer core and speedometer core will be given.

Wire requirements 130 speedometer core Helix W- Layer No. Lead D. i Angle la Degrees 1 1 .018 4 39 1 .0l-'i 4 19 1 .Ol- 4 lll l .015 4 1l 1 017 1 Steel shaft Wire Actual O D .12S/.127. Weight i 2 lbs. per/M Feet. Internal Friction .13.

Deflection Factor:

Wiiidup 154. Unwind 70.

Wire requirements 220 speedometer core Helix Layer N o. Lead Angle Degrees l 1 .017 4 37 .1 .015 4 18 1 015 4 14 1 .017 4 13 1 .024 4 13 1 .033

1 Steel shaft wire.

Actual O. D .2l7/.2l9. Weight 100 lbs. per/H Feet. Internal Friction .00. Deection Factor:

Windup 9. Unwind l5.

When using 220 speedometer core (Example 1) having an outside diameter of .217"/.219 for the core II and using a .138" diameter wire for the coil body, the coil body'wire is wound to provide an overall clearance of`..005/.007" between the outside of the core and the bore of the coil. Assuming the core to be disposed centrally in the bore, there will be a clearance space of between .0025/.0035" between each side of the core and the associated side of the bore. This clearance space is best shown and indicated in Fig. 2 by the numeral I6. Thebody I2 of such a coil will have an outside diameter of approximately .5".

Examples of other more commonly used cores and coils will be given for illustrative purposes. Using 187 speedometer core (Example 2) having an outside diameter of .186/.188 for the core II and using .120" diameter wire for the coil body, the coil body wire is wound to provide an overall clearance of .005/.007 between the outside of the core and the bore of the coil. Assuming the core is disposed centrally in the bore there willbe a clearance space of between .002/.0035 between each side of the core and the associated side of the bore. Such a body I2 will have an outside diameter of about .433.

Using 130 speedometer core (Example 3) having an outside diameter of .125/.127 for the core II and using .080 diameter wire for the coil body, the coil body wire is wound to provide an overall clearance of .005"/.00'7 between the outside of the core and the bore of the coil. Assuming the core to be disposed centrally in the bore, there will be a clearance space of between .0025/.O035" between each side of the core and the associated side of the bore, Such a body I2 will have an outside diameter of about .292".

Thus, it is assured that While the core is per- CFI manently carried by the coil, a relative longitudinal slippage may occur between them in passing around and about a tortuous path as is sometimes presented by a conduit, and this without a complete displacement between the core and coil. Thus, both the core and the coil are in their most freely exible condition readily to follow said path and this without producing a kink or permanent change of form therein. As soon as suiiicient torque is imposed upon the coil, it constricts itself to engage the core so the core affords an internal support for the coil against the action of torque tending to fracture the coil or produce kinks or breaks therein.

In Fig. 1 is illustrated one convenient way to form an attachmentv between the core and the coil. Attachment is provided by reducing the last three coilsV I'I of the body I2, where it joins the end portion I3, thereby tightly gripping the core at that point. This reduced portion of the coil may be provided at the time the coil is formed, in which event the core would then be placed in position to be gripped. Or, if desired, the entire coil may be formed first, the core inserted and roller or die pressure applied along the several coils I'I to reduce the coil locally.

Fig. 4 illustrates another way in which the core may be secured to the coil as by a weld I8, which weld may be made from the end of the portion I3 before the plug I 4 has been applied, if a plug is to be used.

In Fig. l5 the end of the core is shown as being upset or attened to form an enlarged head I9 therefor, which prevents the core, as a whole, from moving longitudinally away from the portion I3, toward the point Where the coil is turned, but still permits the relative slippage between the coil and core when they are being threaded through a conduit having bends, elbows and the like therein, or when the coil is wound upon a storage reel or drum.

In Fig. 6, the end of the core is shown as being indirectly attached to the coil through the medium of the tool carrying plug i4. In this instance the end of the core is welded, as at Eil, in a recess in the inner end of said plug. It will be understood that the part I-3 as in Fig. 1 will taper to join with the main body I2, but without any reduced portion I 'I.

In Fig. '7 the core is shown as having its end xed in a spherical body 2|, located in the inner end of the portion I3 of the coil and which body is of such diameter as to prevent its entrance into the body I2 of the coil. The ball 2| is preferably applied to the end of the core before inserting it into the coil from the open extremity of the end portion I 3 of the coil.

In the use of any of the structures above mentioned, a tool, either hand-operated or motoroperated, is used for turning the coil axially and this in the direction of the arrow in Fig. 2. These tools are or may be conventional and are well known in the art. I have illustrated a motor operated tool 22 having a chuck 25 to grip and turn the coil. After the work or tool end of the coil has engaged an obstruction, for example 24 in Fig. 8, in a conduit and the turning action is continued in the proper direction, torque is built up in the coil and this causes the coil to constrict itself in diameter and engage the core as before explained.

From the above, it will be obvious that in using the method disclosed herein, the coil functions substantially as a free ilexible spring shaft which will readily slide around bends and elbows and past joints in a conduit thereby greatly facilitating insertion of the coil into the conduit. When the work end engages the obstruction, however, and turning movement is imparted to the coil in the manner indicated, froma point outside the conduit, to cause a reduction in the size of the coil and thereby engage the core, the core acts to provide internal support. Tests show greatly improved power transmitting capacity without injury to the coil.

It will also beunderstood that while the core extends substantially throughout the entire length of the coil, the coil and core are only joined or prevented from moving relatively in a longitudinal direction at the work end. Hence, relative longitudinal movement between the coil and core can readily take place as the coil is reduced in diameter and increased in length in the preliminary stages of removing an obstruction from a conduit. Because the core is held at the work end of the coil against backward movement, the core moves along with the coil as it is inserted into the conduit. Therefore, there is always part of the core closely adjacent the work end of the coil under all conditions, in position to support the surrounding coil when the diameter of the coil is reduced, as before explained,

Several examples of coil sizes, cores, space between core and coil and wire requirements, etc. have been given. While these have been found satisfactory in actual use, it should be understood they have been given as by way of illustration and not necessarily by way of limitation, except where the functioning requires such limitation. For example, the annular space between the core and bore of the coil has been given as ofthe order of .0025" .0035 but this may vary, depending upon the size and characteristics of the wire of `which the coil is formed. The purpose of the space between the coil and core is to permit the coil initially to function as a substantially free coil with relative slippage between coil and core and then when subjected to torque, which elongates it and reduces its diameter, to be supported internally by the core whereby to increase the power transmission capacity of a given coil whilst maintaining it in good condition. Hence, while the space between core and coil may be more orless` than that given, it should never for any particular core-coil combination be so small that the freedom of the coil in the initial part of an obstructionremoving Aoperation is impaired to the extent that will cause damage to the coil or lcore when the device is used for its intended purpose andwithin the power range for which the device is designed.

Again, the space between the core and coil should not be too great-otherwise damage to the coil will be caused before it engages the core and is given internal support thereby. Therefore, the maximum space between the core andl l0 that when flexed it will return to normal and not take a permanent kink or set.

Hence, while in describing the invention I have referred in detail to the form, arrangement and construction of and diameters of the parts involved, the same is to be considered only in the illustrative sense and therefore I do not wish to be limited thereto except as may be specically set forth in the appended claims.

I claim as my invention:

l. A device for removing obstructions from conduits and embodying therein a helically wound flexible wire coil having a longitudinal y passageway therein, a flexible core member diswhen the coil is held at one end and is turned coil should be such that it can be taken up by the reduction, under torque action, of the coil diameter before the elastic limit ofthe particular coil wire is exceeded. Hence, the smallest amount of space betweenthe core and coil, which will afford free slippage between coil and core in the initial part of the operation, is generally preferred. l .i

Specification of cores which have been satisfactorily used, have been given, but these too are by way of illustration. For example, wire other than steel may be used where corrosionv is an important consideration. The wire of the core should, however, have spring characteristics so l axially from -a point spaced from said end and in a direction to build up suliicient torque therein, the diameter of said major part of the remaining portion of the coil is reduced to such an `extent that it will engage and be internally sup- 30 tudinal passageway therein, a flexible core member disposed in and having a cross sectional diameter of such lesser size than that of said passageway as to provide a limited clearance space between core and coil, said core being attached to the coil at one point only in the length thereof by means of a weld so as firmly to grip said core, the dimensional characteristics of the major part of the remaining portion of the coil and the core being such that when the coil is held at one end and is turned axially from a point spaced from said end and in a direction to build up suiiicient torque therein, the diameter of said major part of the remaining portion of the coil is reduced to such an extent that it will engage and be internally supported by the core before the elastic limit of the wire of the coil is exceeded. i

3. A device for removing obstructions from conduits and embodying therein a helically wound flexible spring wirecoil having a longitudinal passageway therein, a flexible core member disposed in and having a cross sectional diameter of such lesser size than that of said passageway as to provide a limited clearance space between core and coil, one end only of the core being diametrically enlarged to form an operative connection between coil and core at one point only in the length thereof, the dimensional characteristics of the major part of the remaining portion of the coil and the core being such that when` the coil is held at one end and is turned axially from a point spaced from said end and in -a direction to build up suflicient torque therein, the diameter of said major part of the remaining portion of `the coil is reduced to such' an extent that it will engage and be internally supported by the core before the elastic limit of the wire of the coil is exceeded.

4. A device for removing obstructions from conduits and embodying therein a helically wound fiexible spring wire coil having a longitudinal passageway therein, a ilexible core member disposed in and having a cross sectional diameter of such lesser size than that of said passageway as to provide a limited clearance space between core and coil, and means, of a size greater than that of the major part of the passageway, attached to one end of the core only and positioned adjacent one end only of the coil whereby relative movement of the coil and core at that point is prevented in one direction, the dimensional characteristics of the major part of the remaining portion of the coil and the core being such that when the coil is held at one end and is turned axially from a point spaced from said end and in a direction to build up suiicient torque therein, the diameter of said major part of the remaining portion of the coil is reduced to such an extent that it will engage and be internally supported by the core before the elastic limit of the wire of the coil is exceeded.

5. A device for removing obstructions from conduits comprising' a helically wound flexible spring wire coil having a longitudinal passageway therein, said coil having a work end, a ilexible spring wire core disposed within said passageway and of such lesser diameter than that of the passageway as to provide a limited clearance space between coil and core throughout at least a major portion thereof when the coil is torsionally unstressed, which clearance space is or" such limited size that it can be taken up by torsional reduction of coil diameter before exceeding the elastic limit of the coil wire, and means operatively connecting the coil and core adjacent the work end only of the coil to restrain movement of the core as a whole rearwardly from the work end of the coil, thereby providing for the free slidable relative movement between the remaining Vpart of the coilY and core when the coil is torsionally unstressed whereby when the coil is held against turning movement at the work end and is turned axially from a point spaced from said end, and in a direction to build up suflicient torsional stress, the diameter of the coil will be reduced, thereby taking up the limited clearance between coil and core and causing the coil to be internally supported by the core in such reduced portion of the coil.

6. A device for removing obstructions from conduits comprising a helically wound flexible spring wire coil having a longitudinal passageway therein, said coil having a work end, an annular flexible spring wire core disposed within said passageway and of such lesser diameter than that of the passageway as to provide, when the coil is torsionally unstressed, an annular clearance space between coil and core throughout at least a major portion thereof, which annular clearance space is, when the core is centered within the coil, not greater than .0035", and means operatively connecting the coil and core adjacent the work end only of the coil to restrain movement of the core as a whole rearwardly from the work end of the coil, thereby providing for the free slidable relative movement between the remaining part of coil and core when the coil is torsionally unstressed, whereby when the coil is held against turning movement at the work end and is turned axially from a point spaced from said end, and in a direction to build up suicient torsional stress, the diameter of the coil will be reduced, thereby taking up the clearance between coil and core and causing the coil to be annularly supported internally by the core in such reduced portion of the coil.

7. A device for removing obstructions from conduits comprising a helically wound ilexible spring wire coil having a longitudinal passageway therein, said coil having a work end, a flexible spring wire core disposed within said passageway and of such lesser diameter than that of the passageway as to provide an annular clearance space between coil and core throughout at least a major portion thereof, which annular clearance space is, when the core is centered within the coil, not greater than .0035 nor less than .0025", and means operatively connecting the coil and core adjacent the work end only of the coil to restrain movement of the core as a whole rearwardly from the work end of the coil, thereby providing for the free slidable relative movement between the remaining part of coil and core when the coil is torsionally unstressed whereby when the coil is held against turning movement at the work end and is turned axially from a point spaced from said end, and in a direction to build up sufcient torsional stress, the diameter of the coil will be reduced, thereby taking up the clearance between coil and core and causing the core to be annularly supported internally by the core in such reduced portion of the coil.

,8. A device for removing obstructions from conduits comprising a helically wound exibl-e spring wire coil having a longitudinal passageway therein, said coil having a work end, a flexible spring wire core disposed within said passageway and of such lesser diameter than that of the passageway as to provide a limited clearance space between coil and core throughout at least a major portion thereof, and means operatively connecting the coil and core adjacent the work end Vonly of the coil to restrain movement of the core as a whole rearwardly from the work end of the coil, thereby providing for the free slidable relative movement between the remaining part of coil and core when the coil is torsionally unstressed whereby when the coil is held against turningvmovement at the work end and is turned axially from a point spaced from said end, and in a direction to build up suiiicient torsional stress the diameter of the coil will vbe reduced, thereby taking up the limited clearance between coil and core and causing the coil to be annularly supported internally by the core in such reduced portion of the coil, and whereby the coil will returnV to a larger diameter when relieved of torsional stress.

9. A device for removing obstructions from conduits comprising a helically wound ilexible spring wire coil having a longitudinal passageway therein, said coil having a work end, a multiple strand flexible spring wire core disposed within said passageway and of such lesser diameter than that of the passageway as to provide a limited clearance space between coil and core throughout at least a major portion thereof, the cross sectional dimension of the wire forming the coil being at least several times the diameter of the individual strands comprising the core, and means operatively connecting the coil and core adjacent, the work end only of the coil to restrain movement of the core as a whole rearwardly from the work end of the coil, thereby providing for the free slidable relative movement between the remaining part of coil and core when the coil is torsionally unstressed whereby when the coil is held against turning movement at the work end and is turned axially from a point spaced from said end, and in a direction to build up suicient torsional stress the diameter of lthe coil will be reduced, thereby taking up the limited clearance between coil and core and causing the coil to be annularly supported internally by the core in such reduced portion of the coil, and whereby the coil will return to its larger diameter when relieved of torsional stress.

JOHN V. OBRIEN.

REFERENCES CITEDv The following references are of record in the le of this patent:

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